What Is Climate
and
Climate Change?

Our weather is always changing
and now scientists are discovering that our climate does not stay the
same either. Climate, the average weather over a period of many years,
differs in regions of the world that receive different amounts of sunlight
and have different geographic factors, such as proximity to oceans
and altitude.

Climates will change if the
factors that influence them fluctuate. To change climate on a global
scale, either the amount of heat that is let into the system changes,
or the amount of heat that is let out of the system changes. For instance,
warming climates are either due to increased heat let into the Earth
or a decrease in the amount of heat that is let out of the atmosphere.

The heat that enters into the Earth system comes from the Sun. Sunlight
travels through space and our atmosphere, heating up the land surface
and the oceans. The warmed Earth then releases heat back into the atmosphere.
However, the amount of sunlight let into the system is not always the
same. Changes in Earth’s orbit over thousands of years and changes
in the Sun’s intensity affect the amount of solar energy that reaches
the Earth.

Heat exits the Earth system as the Earth’s surface, warmed by solar
energy, radiates heat away. However, certain gases in our atmosphere,
called greenhouse gases, allow the lower atmosphere to absorb the heat
radiated from the Earth’s surface, trapping heat within the Earth
system. Greenhouse gases, such as water vapor, carbon dioxide, methane
and nitrous oxide, are an important part of our atmosphere because they
keep Earth from becoming an icy sphere with surface temperatures of about
0°F. However, over the past century or so the amounts of greenhouse
gases within our atmosphere have been increasing rapidly, mainly due
to the burning of fossil fuels, which releases carbon dioxide into the
atmosphere. Consequently, in the past one hundred years global temperatures
have been increasing more rapidly than the historic record shows. Scientists
believe this accelerated heating of the atmosphere is because increasing
amounts of these greenhouse gases trap more and more heat.

Complicating Factors
There are many different factors that complicate this system, including
clouds, volcanic eruptions, oceans, and people. Additionally, there
are likely factors that affect climate which we have yet to identify.
Factors interact, resulting in global cooling, global warming, or
even contributing to both. Find out more about some of these processes
by clicking on the link above.